Envelope Proteins of Vesicular Stomatitis Virus: Effect of Temperature-Sensitive Mutations in Complementation Groups III and V

Abstract

All five major viral proteins were synthesized in chicken embryo cells infected with vesicular stomatitis virus temperature-sensitive (ts) mutants of complementation groups III and V and maintained at the nonpermissive temperature. The distribution of these proteins among cytoplasmic cellular fractions separated on discontinuous sucrose gradients was identical for wild-type and tsllI-infected cells. Strikingly different patterns were observed for the G protein in gradients from cells infected by tsV mutants; very little, if any, G protein was found in the lightest fraction. Pulse and chase experiments with wild-type, virus-infected cells showed that protein G moves from the heaviest to the lightest fraction before being incorporated into the virion. After shift down to the permissive temperature (30 C), G protein synthesized at 39.6 C in tsV-infected cells became associated with the lightest cellular fraction and later with the released virions. In contrast, M protein, synthesized at 39.6 C in tsIII-infected cells, was not incorporated into the virions after shift down. These data strongly suggest, first, that M protein is encoded by the vesicular stomatitis gene m, and second, that incorporation of G protein in the lightest cellular fraction is a necessary step of vesicular stomatitis maturation. This step is impaired by tsV mutations.

Brefeldin A redistributes resident and itinerant Golgi proteins to the endoplasmic reticulum.

“…To further test the idea that processing occurred in the ER, we used the temperature-sensitive mutant tsO45. At the nonpermissive temperature of 40°C, tsO45 G protein is restricted exclusively to the ER where it is retained in a misfolded, aggregated state (Lafay, 1974;Zilberstein et al, 1980;Bergmann et al, 1981;Lodish and Kong, 1983;Balch et al, 1986;Doms et al, 1987Doms et al, , 1988. The distribution of tsO45 G at 40°C as detected by indirect immunofluorescence was unaffected by the addition of BFA (not shown), and the protein remained misfolded (Fig.…”

The rubella virus E1 glycoprotein is arrested in a novel post-ER, pre-Golgi compartment.

“…To determine if proteins can enter and leave these structures and reach the Golgi complex, CHOE1 cells were infected with the ts045 strain of VSV. At 39.5~ the G protein of ts045 does not enter the Golgi complex due to a temperature-sensitive transport defect, but when shifted to 32~ the protein rapidly exits the ER and is transported through the Golgi to the cell surface (24,28). When CHOE1 cells were kept at 39.5~ VSV G protein was present in both the PER and the E1 tubular network (Fig.…”

Experiments and Speculation on Antiviral Specificity of T and B Cells

“…The second group of mutants, /5M501 (Knipe et al 1977a, b. Hale et al 1978, and /.yO45 (Lafay 1974) failed to express G at the cell surface at the nonpermissive temperature. Target cells infected with these mutants resisted both virus specific cytotoxic T lymphocyte lysis and anti-VSV antibody plus C mediated lysis at the non-permissive temperature (Table VI).…”